Operating linkage for heavy-duty electromagnetically operated switches



H. E. SCHLEICHER 2,802,919 OPERATING LINKAGE FOR HEAVY-DUTYELECTROMAGNBTICALLY Alig. 13, 1957 OPERATED SWITCHES 2' Sheets-Sheet 1Filed July 24, 1953 l 1 a l INVENTOR.

ATTORNEY-5,

H. E. SCHLEICHER 2,802,919 OPERATING LINKAGE FOR HEAVY-DUTYELECTROMAGNETICALLY Aug. 13, 1957 OPERATED SWITCHES 2 Sheets-Sheet 2Filed July 24, 1953 ATTORNEYS,

United States Patent OPERATING LINKAGE FOR HEAVY-DUTY ELEC-TROMAGNETICALLY OPERATED SWITCHES Harold E. Schleicher, West Hartford,Conn., assignor to The Arrow-Hart & Hegeman Electric Company, Hartford,Conn., a corporation of Connecticut Application July 24, 1953, SerialNo.,370,131

4 Claims. (Cl. 200-404) This invention relates to operatinglinkages forelectromagnetically operated switches and particularly thoseelectromagnetically operated switches in whiclr the electromagnetarmature moves in a plane parallel to but between a back plate and aninsulating base or bases spaced from the back plate, the switch contactsbeing located on top of the base or bases and operating therethrough.Although the invention relates to and is particularly useful inconnection with that type of switch, it is not limited to that use butmay be used elsewhere.

Electromagnetically operated switches are commonly provided in differentsizes to take care of different current and voltage requirements. Fordevices designed to handle heavy currents and high voltages the partsare necessarily large because, in order to handle a heavy current, heavycontacts and terminals are required and hence large strong and sturdysupporting mechanism must be provided and operated. Hence theelectromagnet also must be larger and more massive. Thus differentconditions and circumstances require change in the form and operation ofthe various types and ratings of electromagnetic switches.

The present invention is particularly adaptable for starting switchesand like uses of sizes above 100 H. P. It is desirable in this inventionthat the movable contact separate from the fixed contacts at a rightangle. It is also particularly desirable that there be a sliding motionof the contacts after engagement and before disengagement. This is toclean away oxides and overcome any tendency to weld, which causeditficulties in high current devices. It is also desirable that theoperating mechanism function smoothly and with a minimum amount offriction in view of the large size and considerable weight of the partsthat must be moved. It is therefore desirable that the operatingmechanism employ insofar as possible, pivoted connections between thedriving means or electromagnet armature and the movable contact-carryingparts.

Therefore it is an object of the invention to provide improved operatingmeans possessing the aforesaid desirable characteristics for anelectromagnetically operated switch or controller in which the movablebridging contacts are mounted on one side of an insulating base. and maybe moved toward the base into engagement with the fixed contacts andengage at a right angle.

Another object is to provide operating mechanism for switches of theabove-mentioned sort in which insofar as compatible with their size andmass the operating parts may be economically manufactured and assembled,and will be of minimum weight commensurate with the necessary strength,and will be reliable during long continued operation.

Other objects and advantages of the invention will become apparent as itis described in connection with the accompanying drawings.

In the drawings- Fig. 1 is a side elevation view, partly in section andpartly broken away, of a switch mechanism embodying the invention.

Fig. 2 is an end elevation view of the invention illustrated in Fig. 1but with the insulating base and cover elements indicated in phantom.

Fig. 3 is a vertical section View taken along line 33 of Fig. 2.

Fig. 4 is a perspective view of the invention illustrated in Figs. 1, 2and 3, but with the cover, base and contact elements removed.

Referring to the drawings, the invention is shown as applied to a 3-poleelectromagnetically operated circuit breaker in which the three sets ofmovable contacts are each mounted in identical individual insulatinghousings, each comprising a base 10 and a cover 12 made of moldedinsulating material. Each base may be of elongated rectangular shapehaving mounted thereon spaced, aligned, fixed contacts 14, 14" in theshape of rectangular bars or blocks made from heavy gauge sheet metal ofgood electrical conductivity. Contact buttons 15, 15 of good electricalconductivity are aflixed on the inner ends of said bars in position tobe engaged by a movable bridging contact 16 such, for example, as isillustrated.

and described in my Patent No. 2,534,069, issued December 12, 1950. Forsupporting the insulating bases 10 in parallel arrangement from a metalback or base plate 30 and spaced in front thereof, parallel fabricatedside plates 32, 34 are provided adjacent the side edges of the backplate across the top of which transversely extend a pair of spacedparallel heavy sheet metal supporting bars 36, 38. Preferably thefabricated side plates 32 may be formed from a pair of sheet metalplates welded or secured back to back with their upper ends out-turnedto afford a broad supporting flange for the bars 36, 38. The lower edgesmay also be out-turned to lie flat on the back plate 30. Upon the bars36 and 38 the three insulating bases 10 may be aflixed in any suitablemanner in position for the three hereinafter-describedcontact-supporting insulating posts 18 to extend through apertures inthe center of said insulating bases.

Each of the bridging contacts 16 is resiliently mounted on a square post18 of insulating material. A square stud 18a extends from the top ofeach post and passes. through a square hole in the center of theassociated bridging contact. Pressing said bridging contact on the topof the post and mounted on the stud 18a is a coiled compression spring19 with its lower or inner end pressing on the top or outer surface ofthe contact while its top is engaged and held by a washer 19w fitted ina peripheral slot formed in the top part of the stud.

To move the bridging contact into and out of engagement with the fixedcontact the posts 18 are mounted on a contact-carrying bar 20 extendingtransversely and supported near each end by pairs of closely-spacedparallel legs 22, 22 and 24, 24' (designated, generally, by numerals 22and 24). These legs may be stamped from sheet metal with upper endsturned at right angles forming flanges below and flush against the undersurface of the contact-carrying bar 20.

The electromagnet and the actuating means connecting it with the movablecontact carrier 20, 22, 24 are located between the bases 10 and the backplate 30 so as to be isolated from the switch contacts and terminals.The electromagnetic operating means may consist of a conventionalU-shaped field piece 29 made of laminated magnetic material in thecenter opening of which is located a conventional solenoid coil 54.Within the coil and movable in and out thereof is a T-shaped armature 54also made of laminated magnetic material. The field piece is located inparallel relation to the insulating bases and back plate so that thearmature will move in a plane parallel to the base and the back plate.

In order to transmit the force of the armature and also to translate itsmotion from parallel to the bases into motion of the contact to and fromthe bases, a driving member 55 stamped from sheet metal is loosely andpivotally secured to the armature and is looped around a drive rod 56extending transversely between the side plates 32 and 34 parallel to theplanes of the bases and back plate. The ends of said drive rod arepivotally mounted in an upper corner of a triangular bell-crank drivinglevers 40, 40' each of which has a pivot bearing mounted in a lowercorner by which the bell crank levers are coaxially pivotally mounted ona fixed rod 58 extending transversely between the side plates 32 and 34near their bottom edges.

The motion of the bell-crank levers 40, 40' is transmitted to thecontact carrier by coaxial roller bearing pivotal connections of thelower inner corner of the levers 40, 40 to the lower ends of legs 22,22', 24, 24' of the contact carrier, the pivot pins 44 and 44 passingthrough the legs 22, 22' and 24, 24 respectively and the inner cornersof the bell-crank lying between the legs 22, 22 and 24, 24'respectively.

In order to guide the upper ends of the carrier legs 22, 24, guidelevers 23, 23' extend between legs 22, 22' and 24, 24' respectively andare pivotally connected thereto by coaxial pivot pins 26, 26',respectively, passing therethrough near the tops of said legs.

The guide levers 23, 23 are also pivoted about a fixed pivot rod 25extending transversely between the side supporting plates 32, 34 andlocated in the area between the side supporting plates 32, 34 andlocated in the area between the legs of the contact carrier and one endof the side plates 32, 34 at about the same height as the pins 26, 26.An extension of each lever 23, 23' has a hooked end over which is loopedone end of a coiled tension spring 28, the other ends of said pair ofcoil springs being hooked around coaxial anchor pins 29, 29' fixedlymounted in the lower part of the side plates 32, 34,

respectively.

The springs urge the contact carrier and bridging contacts into opencircuit position.

From the foregoing it will be seen that attraction of Although the fixedcontact sets are shown as mounted on separate bases'they may also bemounted on a single base.

In the larger sizes of electromagnets it is particularly desirable toreduce power losses, and hence to keep the size of the magnet structureto a minimum commensurate with the power needed to move the switchparts. It is also necessary to hold the laminations of the field piece(whether U-shaped or C-shaped) rigidly in order to prevent loss and toreduce hum. Heretofore iron or steel plates have usually been providedon top and bottom of the stack of laminations extending across the gapbetween the legs and often of open-centered rectangular shape.

These plates were held on top and bottom of the field piece by rivetspassing through the whole. I have found that the presence of the metalacross the gap reduced the effective power or, in other words, requiresa larger magnet structure. By bridging the gap above and below the openends of the field piece with heavy insulation blocks 60, 62 which areriveted in place by rivets passing through the field piece, a smallermagnet structure is needed and the power delivered is approximatelygreater.

Modifications within the scope of the invention will occur to thoseskilled in the art and therefore the invention is not limited to thespecific embodiment illustrated.

What'I claim is:

1. In combination, an insulating base, fixed contact means mountedthereon, bridging contact means moving to engage and disengage 's'aidfixed contacts, and mechanism for transmitting a contact moving force tosaid bridging contact means to cause perpendicular engagement of thefixed contacts by the bridging contact means comprising contactsupporting means having parallel arms the armature 54 will causemovement of the drive rod 56 and pivoting of the bell-crank levers 40,40 about their fixed axis 58 in counter-clockwise direction, referringto Figs. 1 and 3. Such movement causes the pins 44, 44' to move towardthe backplate 30 with the contact carrier (18, 20, 22, 24). The axes 58and 25 are so located with respect to each other and to the pivotalconnections of the drive levers 44, 44' and the guide levers 23, 23'that at the instant of engagement of the bridging contact with the fixedcontacts the pivots 26, 26' will be in alignment with a lineperpendicular to the plane containing the points of engagement of saidcontacts (see dotted position Fig. 3). Since such line is determined bythe position of the contacts and carrier legs at the instant ofengagement it is possible then to locate the fixed axes of the drive andguide levers, bearing in mind the desired position of armature at thatmoment.

The armature will have completed most of its travel so that finalmovement thereof will merely compress the contact springs 19 toresiliently hold the bridging contact in engagement with the fixedcontacts. Since the pivots 26, 44 move in arcs, there will be a slightrubbing motion of the contacts after they engage and before theydisengage.

Due to the fixed pivots 25, 28 being on the same side of the contactcarrier legs 22, 22 and to the radii about which movable pivots 44 and26 move not being greatly different, and also to the angles throughwhich drive and guide levers move being small (around 30), the contactcarrier legs remain substantially perpendicular to the aforesaid planeduring their entire movement.

extending perpendicularly from said base, a plurality of lever meanspivotally connected non-coaxially to said supporting arms at spacedpoints which are different distances from said base, fixed pivotalmountings for said lever means located at spaced points to cause saidlever means both to turn in'the same direction when an operating forceis applied to one, one of said lever means having its fixed pivotalmounting further from said arm than the other thus to provide said onewith a longer lever arm than said other, whereby said mechanism movesthe bridging contact means into engagement with the fixed contact meansperpendicularly.

2. In an electric switch, the combination claimed in claim 1 wherein onelever means is in the form of a bell-crank, and operating meansconnected thereto movable in a direction substantially perpendicular tothe movement of said contact supporting means.

3. In an electric switch, the combination claimed in claim 2 wherein thebridging contact means are mounted on an insulating support carried bythe contact supporting means, said support having portions extendingthrough said base on which said bridging contact means are mounted, saidmechanism for moving said bridging contact means being on the oppositeside of the base.

4. In an electric switch, the combination claimed in claim 2 wherein thebell-crank lever means is farther from the bridging contact means thanis said other lever and is the shorter of said two lever arms.

References Cited in the file of this patent UNITED STATES PATENTS1,714,085 Getchell May 21, 1929 1,816,429 Getchell July 28, 19312,283,795 Dahl May 19, 1942 2,310,056 Bendz Feb. 2, 1943 FOREIGN PATENTS150,128 Great Britain Sept. 2, 1920

